A new study has found record quantities of microplastics in sea ice. The study, published this week in Nature Communications, demonstrates “just how pervasive this type of pollution has become in every last corner of our planet,” says Melanie Bergmann, one of the study’s authors. The researchers found extremely high concentrations of plastic in their samples—up to 12,000 particles per liter of sea ice, or about 45,000 particles per gallon. The majority of particles were microscopically small. 

The ice cores were gathered from five regions throughout the Arctic Ocean in the spring of 2014 and summer of 2015. They were taken back to the laboratory, where they were analyzed for their unique plastic “fingerprint”. The BBC reports that the “plastic fingerprint” from the ice samples suggests they were carried on ocean currents from the huge garbage patch in the Pacific Ocean or arose locally due to pollution from shipping and fishing.  More than half of the microplastic particles within the ice were so small that they could easily be ingested by sea life, said Ilka Peeken of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research in Bremerhaven, Germany, who led the study.

“No one can say for certain how harmful these tiny plastic particles are for marine life, or ultimately also for human beings,” she said. The study discovered plastic particles that were only 11 micrometers across, which is roughly one-sixth the diameter of a human hair.

Estimates suggest about eight million tons of plastic move from the land into the ocean every year, with some finding its way into remote areas, such as the Polar Regions and the deep ocean floor.